National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Chiari malformation type 2


Other Names:
Arnold-Chiari malformation; Chiari type II malformation; Chiari malformation type II; Arnold-Chiari malformation; Chiari type II malformation; Chiari malformation type II; Arnold Chiari malformation type II See More
Categories:
This disease is grouped under:
Chiari malformation type 2 (CM type II) is a type of Chiari malformation in which both the cerebellum and brain stem tissue extend into the foramen magnum (the hole at the skull base for passing of the spinal cord).[1] CM type II is usually accompanied by a myelomeningocele (a form of spina bifida that occurs when the spinal canal and backbone do not close before birth), which can result in partial or complete paralysis of the area below the spinal opening.[1] While the severity of CM type II can vary greatly, it can potentially cause severe, life-threatening complications during infancy or childhood.[2] 

The exact cause of CM type II is not known but it appears to be due to defects in the brain and spinal cord that occur during fetal development.[2] Treatment includes surgery to ease symptoms and/or stop the progression of damage to the nervous system. For most people, surgery improves or stabilizes symptoms. Some people may require more than one surgery.[1]
Last updated: 9/11/2017

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
30%-79% of people have these symptoms
Agenesis of corpus callosum 0001274
Percent of people who have these symptoms is not available through HPO
Arnold-Chiari malformation 0002308
Ataxia 0001251
Bulbar signs 0002483
Cervical myelopathy 0002318
Cyanosis
Blue discoloration of the skin
0000961
Dysphagia
Poor swallowing
Swallowing difficulties
Swallowing difficulty
[ more ] 		0002015
Feeding difficulties
Feeding problems
Poor feeding
[ more ] 		0011968
Generalized hypotonia
Decreased muscle tone
Low muscle tone
[ more ] 		0001290
Gray matter heterotopia 0002282
Hydrocephalus
Too much cerebrospinal fluid in the brain
0000238
Inspiratory stridor 0005348
Limb muscle weakness
Limb weakness
0003690
Multifactorial inheritance 0001426
Muscular hypotonia
Low or weak muscle tone
0001252
Myelomeningocele 0002475
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Occipital neuralgia 0012318
Opisthotonus 0002179
Syringomyelia
Fluid-filled cyst in spinal cord
0003396
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Last updated: 7/1/2020
Chiari malformation type 2 usually occurs sporadically (in people with no family history of the condition). However, the exact cause is not known. Genes may play a role in predisposing a person to the condition, but environmental factors (such as lack of proper vitamins or nutrients in the maternal diet during pregnancy) may also contribute to the condition.[1]

There have been reports in the medical literature of families in which more than one family member had a Chiari malformation.[2] However, limited information specific to familial cases of Chiari malformation type 2 is available.

Last updated: 9/11/2017
People with Chiari malformation type II are typically treated with surgery. Surgery may include closure of open neural tube defects shortly after birth, treatment for hydrocephalus (most often by use of a shunt), and posterior fossa decompression (creating more space for the cerebellum and relieving pressure on the spinal cord). Medical issues may involve management of neurogenic bowel and bladder, neonatal feeding difficulties, respiratory failure, and apnea.[3]

As with any form of surgery, there are risks associated with surgery to treat Chiari malformations. Sometimes, surgery leads to no improvement or even worsening of symptoms.[4] For example, if nerve injury in the spinal canal has already occurred, surgery will not reverse the damage.[5] However, most people who have surgery have improvement of symptoms afterwards. Even if symptoms do not improve significantly, surgery might prevent existing symptoms from worsening.[4]
Last updated: 9/11/2017
The long-term outlook depends on the nature of the malformation and the symptoms present in each person. Although some people experience a reduction of symptoms, there is no guarantee that surgery will help every person. Nerve damage that has already occurred usually cannot be reversed with surgery, and pain from nerve damage can be difficult to treat. Some people may need repeat surgeries.[6]
Last updated: 9/11/2017

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • The Centers for Mendelian Genomics program is working to discover the causes of rare genetic disorders. For more information about applying to the research study, please visit their website.
  • ClinicalTrials.gov lists trials that are related to Chiari malformation type 2. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Chiari malformation type 2. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • What is the recurrence risk in another pregnancy? See answer


  1. Chiari Malformation Fact Sheet. National Institute of Neurological Disorders and Stroke (NINDS). June, 2017; http://www.ninds.nih.gov/disorders/chiari/detail_chiari.htm.
  2. Chiari Malformations. NORD. 2014; http://www.rarediseases.org/rare-disease-information/rare-diseases/byID/85/viewAbstract.
  3. Khoury C. Chiari malformations. UpToDate. Waltham, MA: UpToDate; June 28, 2017;
  4. Chiari malformations. Brain & Spine Foundation. June, 2015; http://www.brainandspine.org.uk/chiari-malformations.
  5. Chiari malformation. Mayo Clinic. September 29, 2016; http://www.mayoclinic.org/diseases-conditions/chiari-malformation/diagnosis-treatment/treatment/txc-20249732.
  6. Chiari Malformation. American Association of Neurological Surgeons. http://www.aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Chiari-Malformation. Accessed 9/11/2017.